Electrical reproducer for disk records



Nov. 6, 1934. H. HUBNER ELECTRICAL REPRODUCER FOR DISK RECORDS Filed Oct. 25, 1932 Patented Nov. 6, 1934 UNITED STATES.

ELECTRICAL REPRODUCER FOR DISK RECORDS Hanns Hiibner, Berlin-Lichterfelde, Germany, assignor to Carl Lindstriim Aktiengesellschaft,

Berlin, Germany Application October 25, 1932, Serial No. 639,507 In Germany November 23, 1931 3 Claims.

In the hitherto known electrical reproducers or pick-ups for disk records the armature is generally mounted in roller bearings which are provided with rubber damping or the known knife edge bearings are used.

The knife edge bearing has in itself the advantage of possessing a stationary axis of rotation about which the oscillations take place .so that deviations of the form of the curve of the current produced in the pick-up from the ideal sine form, that is non-linear distortions, are to a large extent avoided.

The hitherto known knife bearings, however, have the disadvantage that on account of their lack of resilience, resonances very easily occur in the lower sound register (tone arm resonance) and also further undesirable resonances occur in the neighbourhood of the natural frequencies determined by the elasticity of the securing means and the mass of the armature in the upper sound register so that such pick-ups are inclined to distortion of the transmitted sounds.

This invention has the object of avoiding these disadvantages of the hitherto known electrical reproducers or pick-ups for disk records. According to the invention this object is achieved in the electrical reproducer for disk records with armature mounted on knife edges by the whole knife edge bearing being mounted in an elastic material (rubber or the like) which is yielding in a direction perpendicular to the axis. The device is preferably constructed in such a manner that for holding the knife edges in the knife edge bearing a leaf spring is provided which bears on at least one of the parts connected by it (knife edge or hearing) through the intermediary of a damping elastic material (for example rubber). The bearing may advantageously be arranged in the opening of the pole shoes of a four-pole magnet system. On account of the whole knife edge bearing being mounted in an elastic material, a sufficient resilience of the knife edge bearing with the large amplitudes of the low frequencies is obtained and thus a damping of any resonances occurring in the lower sound register is secured without the efliciency of the knife edge bearing with its known advantages being detrimentally affected.

On account of the armature being secured in the knife edge bearing by a spring which presses the knife edges against the bearing while the spring bears against at least one of the parts connected by it through the intermediary of a damping elastic material, the second resonance points (in the upper sound register) are also made ineffective. Thus, while retaining the advantages of the known knife edge bearings, the

disadvantages hitherto inherent in such bearings are avoided.

In the accompanying drawing a constructional example of the electrical reproducer is illustrated diagrammatically.

Fig. 1 is a cross-section on the line 11-17 of Fig. 2, and

Fig. 2 is a longitudinal section.

The armature 1 is provided in a manne known per se with the knife edges 2 which bear against the knife edge bearings 3. Over the knife edge bearings 3 and the knife edge members 2, elastic tubular members 4 of rubber, constructed in the form of a hose, are placed which form the elastic bearing. The armature 1 engages with centrally disposed pins 8 over the middle part of a leaf spring 5 which ensures that the knife 7 edges 2 will bear firmly against the knife edge bearing 3. The leaf spring 5 lies on the rubber dampers 4 which enclose the whole knife edge bearing. The whole knife edge bearing with the elastic envelope is preferably mounted in bearing members 6 which are secured in the two pole shoes 7.

Having now fully described my invention what I claim and desire to protect by Letters Patent of the United States of America is:

1. In an electrical reproducer for disk records, an armature having oppositely extending members provided on their upper sides with knife edges, bearings having knife edge recesses in their lower sides and bearing on said knife edges, and tubular elastic damper members extending around and enclosing said knife edge members and said bearings and active to frictionally resist relative angular movement between said knife edge members and said bearings and thereby efiect damping of the points of resonance.

2. Apparatus as claimed in claim 1, including a spring connected to the armature and bearing downwardly on the tubular elastic damper members.

3. In an electrical reproducer for disk records, an armature having oppositely extending members provided on their upper sides with knife edges, bearings having knife edge recesses in their lower sides and bearing on said knife edges, tubular elastic damper members extending around and enclosing said knife edge members and said bearings, a spring connected to the armature and bearing downwardly on the tubular elastic damper members and a pole element having bearing members in which the said tubular elastic damper members and hence also the armature and its bearings are mounted I-IANNS HUBNER. 

